Until now the Children’s Health Insurance Program, known at CHIP, has had bipartisan support. But House Republicans have hit a new low by playing games with it — allowing funding for the program to expire Sept. 30, putting the health coverage for 9 million children at risk.

Congress needs to reauthorize CHIP for five years. It’s up to the Republican leaders who’ve been stalwart supporters of care for children to keep their party from using CHIP as a weapon in the war on Obamacare.

California has more at stake than any other state. It received $2.4 billion in federal CHIP funding in 2016, allowing the state to reach historic levels toward its goal to provide coverage for every child. Since 2001, the CHIP program has helped California reduce the rate of uninsured children from 14 percent to 3 percent.

If the program is not reauthorized, California will run out of CHIP funds by December, and 1.3 million kids — including more than 200,000 in the Bay Area — will lose their health care coverage.

Republicans and Democrats had already agreed to allow the federal government to gradually reduce its matching rate from 88 cents to 65 cents for every dollar states spend on children’s health care. But House Republicans insist that funding for the program come from cutting billions from Medicare and public health prevention programs established by the Affordable Care Act. Another GOP proposal would substantially raise Medicare premiums for wealthy beneficiaries, which is also a non-starter for Democrats.

Research that led to the CHIP program in 1997 found that children with access to regular medical care are demonstrably healthier than kids who are uninsured. That means they do better in school and are far more likely to not only get diplomas but also go to college.

This inspired Republican Sen. Orrin Hatch to team with Democratic Sen. Ted Kennedy on what was widely regarded as one of the best bipartisan health care measures ever passed by Congress.

Fortunately, Hatch hasn’t forgotten. He is working across the aisle with Oregon Democratic Sen. Ron Wyden on a more acceptable final proposal.

The need to reauthorize CHIP goes beyond the moral imperative to care for children: When kids don’t receive routine health checkups, they often wind up in hospital emergency rooms at far greater public cost. According to Kelly Hardy of Children Now, it costs $136 a month to provide basic health insurance for California kids but an average of $785 every time a child is taken to an ER. And children who get care only in emergencies are far less healthy.

Congress needs to put politics aside and make the smartest investment possible in healthier children.